There are two types of vehicle construction generally used today: body-over-frame construction, which uses a separate steel frame to which the body is bolted at various points; and unibody construction or body-frame-integral, in which the body sections serve as structural members. Pickup-type vehicles are typically built with body-over-frame construction as the flexibility to do multiple body styles is very limited in a body-frame-integral truck. However, body-over-frame construction truck designs are typically mass intensive.